Freiburg 2024 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 71: Nano-Optics
Q 71.1: Talk
Friday, March 15, 2024, 14:30–14:45, HS 3219
Near-field Fano spectroscopy of MaPbI3 nanoparticles — Jinxin Zhan1, •Tom Jehle1, Sven Stephan1, Sam Nochowitz1, Petra Groß1, Ekaterina Tiguntseva2, Sergey Makarov2, and Christoph Lienau1 — 1Universität Oldenburg, Germany — 2St. Petersburg, Russia
Dielectric nanoparticles particles have optical shape resonances that confine light on the nanoscale in localized modes with well-defined spatial field profiles. A particularly interesting example are halide perovskite nanoparticles, for which the coupling between excitons and Mie modes results in Fano lineshapes in the spectral domain [1]. Here, we use a new broadband, interferometric sSNOM technique [2] to probe the time dynamics of the local optical near-fields of such particles. We measure amplitude and phase of the scattered light field in a broad spectral range and with 10 nm spatial resolution. Direct Fourier transformation gives the time dynamics of the local electric field, recorded with sub-cycle resolution. We uncover biexponential near-field decays with a characteristic destructive interference dip after a few fs. In the spectral domain, this corresponds to a Fano resonance with an unual 2π phase jump. We show that this signature arises from the intereference between spectrally broad dipole and narrow quadrupole resonances of the particles. Our results give new insight into the optical properties of high-index, active semiconductor nanoparticles with intriguing applicatoins for nanoscale all-opticals switching and lasing. [1] Tiguntseva, E. Y., et al. Nano Lett. 2018, 18 (2), 1185-1190. [2] Zhan, J., et al. Advanced Photonics 2020, 2 (04).
Keywords: Halide Perovskite nanoparticles; Optical near fields; sSNOM; Spectral interferometry; Mie resonances